Arc-welding system



A. M. BENNETT, W. B. ELLIOTT, AND W. OBLENIS.

ARC WELDING SYSTEM. APPLICATION FILED mm. 14, 1918.

1,415,012. e ted May 9, 1922..

INVENTORS 0 MATTORNEY UNITED, STATES'PATENT OFFICE.

ALAN M. BENNETT, WILLIAM B. ELLIOTT, AND WILLIAM OIBLENIS, F WESTFIELD,

NEW JERSEY, ASSIGNORS, BY MESNE ASSIGNMENTS, TO BURKE ELECTRIC COM- PANY.

ARC-WELDING SYSTEM.

Specification of Letters Patent.

Patented May 9, 1922.

To all uilwm it may concern;

Be it known that we, ALAN M. BENNETT,

WILLIAM B. ELLIOTT, and WILLIAM OBLENIs', citizens of the United States, all

residing at Westfield, county of Union, State of New Jersey, have invented new and useful Improvements in Arc-Welding Systems, of which the following is a specification.

This invention relates to a system for welding, brazing or otherwise treating metals by means of the electric arc.

Where the arc is fed from a constant potential, it is very unstable. This has been overcome to some extent by placing resistance in circuit with the are but this is a wasteful proceeding. A much more efiicient method is to vary the voltage impressed on the arc electrodes according to the resistance of thearc. For this purpose the generator supplying the voltage may be provided with a bucking series field which will lower the excitation of the generator, and consequently.

lower the voltage, when the current increases due to lowering of the resistance of the arc circuit as by decrease in the resistance of the arc.- If however, such a series field is designed to maintain a substantially constant current under normal working conditions it may fail to produce the desired effect upon the circuit under other conditions such, for instance, as those which pre- Vail at'the striking or formation of the arc.

It is the main object of the present invention to provide means responsive to circuit conditions for regulating a bucking series field so that it will have the desired effect under different circuit conditions.

Other and ancillary objects of the invention will appear hereinafter.

In the accompanying drawing which illus trates the invention, is shown a diagram of apparatus and connections of a system for arc welding which embodies the invention.

Referring to the drawings, the apparatus comprises a direct current generator comprising an armature 1, a separately excited field 2 and a series field 3, the shunt and series fields opposing each other. The separately excited field isconnected by conductors 4 and 5 with a suitable source of exciting current and has connected in series with it the adjustable rheostats 6 and 7. The rheostat 6 has its terminals connected by con ductors 8 and 9 with the contacts of a relay 10. When the relay is energized, these contacts are closed,'placing a short circuiting shunt about the rheostat.

The coil of the relay 10 is connected in series with the series field 3 between one terminal of the generator and the electrode 11; the other terminal of the generator is connected with the work 12.

An adjustable resistance 13 isadapted to be connected across the series field 3 by the energizing of the relay 14, this shunt being opened when the relay is de-energized. The coil of this relay has its terminals connected with the electrodes 11 and 13 respectively, so as to be in shunt to the arc.

, The rheostat 7 is so adjusted as to give the desired strength of separately excited field during normal working while the rheostat 6 is so adj7usted that,- in conjunction with the rheostat there will be a suitable voltage when the electrodes are brought together to initiate the arc. Assoon as the electrodes have been brought together and current flows, therelay 10 will be energized, thereby short ci-rcui'ting the rheostat 6 so that the separately excited field will be increased. The larger resistance included as the electrodes are brought together causes a weaker separately excited field at that time and therefore a reduction int-he generator voltage which prevents excessive rush of current. As the arc is drawn, however, and its resistance introduced into the circuit, a higher voltage is desired for normal working and consequently as soon as current flows a portion of the resistance in the separately excited field cincuit is cut out as described.

The series field, which, as before stated, opposes the separately excited field, is made stronger than that re uired for normal working so that when t ere is a tendency to a rush of current as, for instance, by the electrodes being in contact, it will oppose the se aratel excited field to such an extent that the resu tant excitation of the machine, and consequently the voltage, will be reduced to a point at which an excessive rush of current will be prevented. When, however, the

are is drawnso that there is a sufficient voltage drop across the arc, the relay 14 will become energized and close the shunt about the series field, the resistance 13 being adjusted to a value which will cause the right proportion of current to traverse the series field so as to produce the desired effects under normal working conditions. Under such conditions, the stability of the arc is maintained by reason of the fact that if for any reason the resistance is increased, the current will be decreased. This will decrease the opposition by the series field to the separately excited field and thevoltage impressed on the arc. will be correspondingly increased. On the other hand should the resistance of the arc be decreased, the increased current resulting will strengthen the opposition by the series field to the shunt field. This will cause a loweringof the voltage. 'In this way the voltage impressed on the arc may be made directly .proportional to the resistance thereof and the current; in the are maintained substantially constant.

While the invention has been illustrated in what is considered its best application, it may have other embodiments without departing from its spirit, and is not therefore limited to the structure shown in the draw- TVhat we claim is-- 1. The combination of a variable resistance circuit, a generator supplying said circuit, said generator comprising a field wind ing and a series field winding opposed to the aforesaid field winding, and means responsive to increasing in working voltage for reducing the effect of the series field winding on the generator voltage.

2. The combination of a varlable resistance circuit, a generator, said generator comprising a field winding and a series field winding opposed to the aforesaid field winding, a shunt for said series field winding, and means responsive to increase in circuit voltage for closing said shunt comprising a second shunt circuit subjected to the working voltage.

3. The combination of a variable resistance circuit, a generator, said generator comprising a field winding and a series field winding opposed to the aforesaid field winding, a shunt for said series field winding,

' ance circuit, a generator, said generator comprising a field winding and a series field winding opposed to the aforesaid field winding, means responsive to working current for controlling the first mentioned field winding, and means responsive to working voltage for controlling said series field winding.

6. The combination of a variable resistance circuit, a generator, said generator comprising a separately excited field winding and a series field winding opposed to said separately excited field winding, and means responsive to working voltage and working current respectively for respectively controlling said series and separately excited field windings.

7. The combination of a variable resistance circuit, a generator, said generator comprising a separately excited field winding and a series field winding opposed to said separately excited field winding. a resistance for said separately excited field winding, a relay in series with the load circuit for controlling said resistance, a shunt for the series field winding, and a relay in shunt with the load for controlling said shunt for the series field winding,

8. The combination of a variable resist ance circuit a generator having a main energizing win ing adapted to develop an. open circuit voltage, another winding bucking said main winding, means for increasing the current through said main winding upon closing of the generator armature circuit, and means for controlling the current through said second winding by variations in the load voltage.

9. The combination of a variable resistance circuit, a generator having a main energizing winding adapted to develop an open circuit voltage, another winding bucking said main winding, means for relatively adjusting the currents through said windings, means for increasing the current through said main winding upon closing of the generator armature circuit, and means for controlling the current through said second winding by variations in the load voltage.

10. The combination of a variable resistance circuit, a generator having a main energizing winding adapted to develop an open circuit voltage, another winding bucking said main winding, means for increasing the current through said main winding upon closing of the generator armature circuit, means for controlling the current increase in said main winding, and means for controlling the current through said second winding by variations in the load voltage.

11. The combination of a variable resistance circuit. a generator having a main energizing winding adapted to develop an 0 Nu, circuit voltage, another winding bucking said main Winding, means for relatively ad through said second Winding by variations JuSting the currents through said windings, .in the-load voltage. means for increasing the current through .In te'stimonywhereof We have signed this 10 'said main Winding upon closing of the genspecification this 23rd day of February 1918.

erator armatu're'circuit, means for control- 7 ALAN ETT. ling. the current increase insaid main wind- WILLIAM ELLIOTT; ing, and means for controlling the current WILLIAM OBLENIS. 

